A magnetoresistive angle measuring instrument formed by a magnetoresistive angle sensor and a permanent magnet encoding disc is applicable to a magnetic encoder, a rotary position sensor and other fields. Under normal circumstances, for magnetoresistive sensors such as TMRs and GMRs, plane X—Y type magnetoresistive sensor chips are employed, measurement on a rotation angle of the permanent magnet encoding disc is implemented by measuring magnetic field components in X-axis and Y-axis directions and calculating a magnetic field included angle, but it mainly has the following problems:
1) as GMR and TMR magnetoresistive sensing units each have a one-way planar magnetic field sensitive direction, it is common to rotate a sensor slice in an X sensitive direction by 90 degrees to obtain a sensor slice in a Y sensitive direction, the two slices are connected through binding and are packaged in a same chip, but such an X-Y magnetoresistive angle sensor chip affects measurement precision of the sensor because the mounting positions between the slices are related to operations on the slices during packaging, and also has a problem of thread connection between the slices; therefore, the process is relatively complicated;
2) for a bridge structure of a linear X, Y magnetoresistive sensor formed by GMR and TMR magnetoresistive sensor units, when a push-pull structure is employed, it is common to deflect one of the slices formed by two bridge arms by 180 degrees relative to the other to implement opposite magnetic field sensitive directions of a push arm slice and a pull arm slice, the two slices need to be mounted at different positions on the chip, and a connection between the slices is implemented through binding, which may also affect the measurement precision of the sensor, and increase complexity of the process; and
3) for an X-Y angle sensor chip, its working position is located above a position of a rotation plane region parallel to the permanent magnet encoding disc, and thus the mounting space of the permanent magnet encoding disc is smaller than the size of the encoding disc, and it is necessary to increase the size of the encoding disc to ensure that the chip has a large mounting space and a large magnetic field homogenous region.